I just love the sound of those old Triumphs and MGs with the exhaust burble and blat every time you took your foot off the gas. Just what made them sound like that? A combination of low compression, high revs, and poor carburation? Would it be possible to make any other engine sound like that?
And Burned Valves.
What I Liked Was The Sound Of A BSA Lightning Rocket Or Triumph Bonneville With The 180 Degree Crank.
You could make an engine sound like that, but who wants to walk frequently and work on electrical problems all the time ?
CSA
You absolutely could make an engine sound like that. Mazda made their Miata engine sound exactly like that. Well, without the “blat” that was indicative of the old carbs…and withouot the “stumble” when you punch the throttle that was indicative of the fuel supply taking a moment to catch up with the now-unrestricted incoming air.
Tom McCahill (of Mechanix Illustrated fame), compared the sound of a Triumph TR2 to " A Bronx lad cheering visiting dignitaries"!!
Whatever sound turns you on!
The first time I drove a Miata I thought I’d stepped back in time into an MGB. When it didn’t break in the middle of the drive I realized I couldn’t have.
A camshaft that causes a lot of valve overlap will do that. It makes the engine able to run faster at high RPMs by opening the valves longer (more valve duration). A 289 with just a “Y” pipe would sound great too.
I had an old Sunbeam Alpine (not the Tiger) and it was neat to listen to along with being a blast to drive. It was actually a pretty reliable car and the only problem I ever had with it was one alternator failure.
The best sounding car I’ve ever owned in my life was my old 1959 Corvette with the 283 and duals out through the bumper ends.
On a beautiful evening with the top popped off it I could just drive around in that thing all night listening to it. It’s hard to describe but a guess a silky growl may be close.
It sounded fantastic right up to the second it broadsided a pickup. 
Everyone posting to this thread has missed the boat. The greatest exhaust sound is the old Ford flat head V-8 with dual exhausts and the proper straight-through mufflers.
I wasn’t aware that Triumph ever made a Bonneville with a 180 degree crank. I knew that they offered a traditional Britbike 360 degree crank for the Bonneville and a 270 degree crank for the cruiser and scrambler versions.
Honda 350s had 180 degree cranks and they sort of sounded like high rpm John Deere tractors, which also used 180 degree cranks.
My son put Flowmaster mufflers on his '68 Ford Galaxie 2-door with 302 V-8… it sounded really nice… almost as good as my brother’s '66 Healey (with Abarth muffler).
You Are Probably Correct, But The Bonnevilles Sure Had A Wonderful Exhuast Note. I Saw One In A Gas Station In A Small Town We Were Passing Through Last Summer. The Whole Family Had To Wait With Me So I Could Hear It Fire Up, Sit Loping, And Then Drive Away.
CSA
I think some of the best sounding cars are the last generation of Mustang V8s. But I’m pretty pleased with what Chrysler’s done with the stock duals on the Hemi in my 300C. Not loud, but a nice tone. My MPG would be a mile or two higher if I didn’t like the sound so much 